Learn the differences between softwoods and hardwoods, their lumber grades, uses and tree trunk structure.
There are two kinds of wood – softwoods and hardwoods. Contrary to their names, the “hardness” of the wood species does not define the characteristics. See the differences noted below.
Softwoods
- Wood from coniferous (with needles)
- Evergreen trees that grow quickly and can be cut easily
- They tend to keep their needles throughout the year
- Softwoods are frequently used as building materials
- Examples of softwood trees are:
- Cedar
- Douglas fir
- Juniper
- pine
- redwood
- spruce
- yew
Hardwoods
- Wood from broad-leaved trees such as oak, ash or beech
- These are deciduous trees that shed their leaves during autumn and winter.
- Are more likely to be used in high-quality furniture, cabinetry, and flooring
- Examples of hardwood trees are:
- Beech
- Hickory
- Mahogany
- Maple
- Oak
- Teak
- Walnut
Tree Trunk Structure
Growth Rings
- Each year, a tree adds to its girth, the new growth being called a tree ring.
- The most recently formed tree ring is the new wood near the outer part of a tree's trunk, just beneath the bark.
- The oldest rings are smaller and near the center.
Cambium
- Is the cell layer of the growing part of the trunk
- It annually produces new bark and new wood
Dead Bark
- Is the outer bark of a tree, which is mostly dead tissue.
- Is the tree's protection from the outside world.
- Is continually renewed from within and helps keep out moisture in the rain, and prevents the tree from losing moisture when the air is dry
- Insulates against cold and heat and wards off insect enemies
Sapwood
- Is the living part of the tree, the outer portion within the bark of the tree
- Is typically lighter in color than heartwood
- Brings water and nutrients up from the roots through tubes inside of the trunk to leaves and other parts of the tree
- The untreated sapwood of virtually all species has very little decay resistance.
- As the tree grows, sapwood or xylem cells in the central portion of the tree become inactive and die. These dead cells form the tree’s heartwood.
Heartwood
- Is the dormant, inner, and darker section of the wood
- Is far less susceptible to decay and fungus
- Has much less moisture than sapwood which means less shrinkage when dried
- The heartwood of some wood species is naturally termite-resistant.
Live Bark
- The inner, living bark is comprised of vascular tissue, called phloem, which serves as a conduit for the transport of sugars produced by photosynthesis in leaves to the rest of the tree.
Pith
- Is the oldest part of the tree, at the very center
Medullary Rays
- Are the thin horizontal rays that extend radially from the core of the tree toward the bark, perpendicular to the growth rings
- Are essential and serve as a link between pith (center) and the periphery of the live tree
- Perform various functions like food storage and transport of food and water